Dementia and Alzheimer’s are growing problems in many Western nations as people are living longer. While a treatment for these cognitive conditions still evades detection, there are certain behaviors and lifestyle choices that are known to exasperate the issue. It now seems that retirement might be one of them.

A new study carried out by researchers over at University College London has found that those looking forward to an early retirement might want to take stock of what they will be filling their new-found time with. As people stop working, their cognitive function starts to decline rapidly, most likely as a result of the sudden cessation of regular mental stimulation.

The work was carried out as part of the university’s long-term health investigation called the Whitehall II Study. It has been tracking 3,433 civil servants over a period of 30 years. For the 14 years running up to retirement, and then another 14 years afterward, the researchers have been regularly testing the participants using a range of examinations, including memory assessments, allowing them to track how different events are affecting them.

And it seems that retirement is a significant hit on people's mental health. The researchers found that when people did eventually retire, they experienced cognitive decline in their verbal memory 38 percent faster than before they stopped working. Publishing their results in the European Journal of Epidemiology, they concluded that the act of retirement significantly accelerates cognitive decline.

“It makes it more likely that dementia will set in earlier,” Professor Cary Cooper, an expert in organizational psychology, told The Telegraph. “We know the more cognitively active you are the more it offsets the risk of dementia. I'm not talking about doing Sudoku but doing something completely different from your job – so if you worked in the civil service all your life, why not go and help out in a hospital or teach?

“The most important thing is to interact with people.”

Interestingly, while the level of work that people were undertaking slowed the decline during employment – possibly reflecting how mentally demanding the job was – in retirement this made no difference. People from all paygrades saw the same precipitous mental decline when they stopped.

Basically, the researchers stress how important it is to continue undertaking mentally stimulating activities in order to alleviate the increase in rate of cognitive decline that can happen after retirement.